Adding "BSD 3-Clause" as a valid license (#13934)

We already have "BSD-3-Clause" as a valid license, but there's a variant
with a space instead of a '-' being used by js-base64 that we need to
accomodate for.

tasks/config/licenses.js

@@ -20,6 +20,7 @@ module.exports = function (grunt) {
         'BSD-3-Clause',
         'BSD-3-Clause AND MIT',
         'BSD-3-Clause OR MIT',
+        'BSD 3-Clause',
         'BSD-like',
         'CC-BY',
         'CC-BY-4.0',